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I have read in some archived posts that using parallel cathode bias resistors of different values can result in a "ghosting" effect.
Apparently this "ghosting" effect can be heard on high EF speakers, but not readily detected on lower EF speakers.
Now what about 2 resistors of equal ohmic value but different wattage ratings?
Would the "ghosting" effect also apply to that scenario?
Also, is the "ghosting" effect more audible on the driver stage vs. finals?
What should the builder be listening for?
I needed (2) 1K resistors in parallel but had to use 1/2W and 1/4W to get the value I needed for a 6SN7 driver stage cathode biasing.
DT 667
Follow Ups:
A single 680 Ohm should work fine, and it is a commonly available value.
Correct.
I am using a 1K and 2K resistors in parallel.
They measured 675 ohms in the circuit.
Glad to see that you were paying attention.
I needed to lower the Rk so I could get enough compliance voltage on top of the C4S to set the current source to 5ma.
Since I use a pot to trim the current setting resistor, selecting a higher value Rk was not a problem.
DT 667
is there some improvement in sonics when using satanic valued resistors?
.
Don't worry about it and enjoy your hobby .
If you believe in all that shit then you are likely to develop a personality disorder like some others around here...
Al
Just bung it in and forget about it. If you believe in ghosts, that's what you will hear/see. If you don't, you won't.
Stick with the 99% deal; the big picture. The remaining 1%, which we are talking about here will change from day to day, your mood, the phase of the moon and so on.
cheers,
Stephen
You forgot to mention biorhythms , sunspots and what you had for tea ;)
Al
I would believe this 'ghosting' could only possibly occur in two tuned series RC circuits with a different phase from one another whereas the parallel resistors are only a resistive element with a combined single value as far as the circuit is concerned.
Hi Neff,
Its far more complex than that. I have found, where you return a resistor on a ground buss will effect "ghosting", and have a sonic signature, sometimes bad, sometimes OK.
Jeff Medwin
Moving a part's "ground" end to different locations on a ground bus can have a real effect, since the current flow along the bus gives voltage differences between two different locations. Current is local, but voltage is always a difference.
(At work, I have replaced the term "ground" with "g-word" to remind co-workers to be careful about what they mean.)
Yes Tim,
Thanks. I self-learned that in 1987 on a 7 chassis P-P-P 6B4G lab amp I built for myself. Was cool to see someone else beside me and Dennis acknowledge this occurs.
Good post .
Jeff Medwin
If parallel resistors of non-identical values "ghost" what does that suggest about what parallel caps of dissimilar values must do.
dave
Dave,
Hi. The Rk resistors are made to be identical, so as not to ghost.
Multiple bypass film caps are purposely selected to be non-identical, and serve a different function.
Each value of film Rk bypass cap will play a different part of the audio spectrum, and a linear-sounding "overall combination" of multiple bypass film cap values gets to be selected and determined by ear.
A single Rk film cap will "tune" to the single cap's value. Film Rk caps are not linear when playing music, despite rudimentary sine wave bench testing.
Cheers,
Jeff Medwin
Multiple bypass film caps are purposely selected to be non-identical, and serve a different function.
could it be that function is to 'ghost'?
dave
.
in fact, number of resistors should be equal to a prime number between 3 and 11.
give it a try and trust your ears.
This is why I keep coming back to Asylum everytime I escape...
-3db
But does this apply in a zero gravity situation, curious minds really wanna know !!
What 'cha running for a home hi fi ??
Jeff
Hi!
Whenever you apply two physical things to the same point of force application, any differences between the two objects will show up in the forces that emanate from this combo.
If you are parallelling two resistors on your cathode, simply make each one completely identical to the other one. In practice, this means better than 1/10th percent matching. Of course the same brand and wattages is also required.
---Dennis---
No industry professional or manufacturer has contributed as much to help the DIYer advance in his art than you have. Please stick around.
> No industry professional or manufacturer has contributed as much to help
> the DIYer advance in his art than you have.
Absolutely agree!
Not Allen Wright.
Not Kevin Carter.
Not Mike LaFevre.
Not Dan Schmalle.
Not Morgan Jones.
Not John Broskie.
Not Joe Curcio.
Not Kurt Strain.
Not Herb Reichert.
...and so on. Maybe others can add some more names to the list of industry professionals and/or manufacturers who have NOT contributed as much to the advancement of DIY audio art as Dennis has.
Have a nice day,
-Henry
Sorry Henry,
But I would expect better than that, from you.
Regards,
Jeff Medwin
You must have missed my sarcasm, Jeff. I don't actually think Dennis has contributed anything of significance to the art of audio design.
Hope this helps.
-Henry
Hi Henry,
I didn't miss it at all. You are entitled to any opinion you want to hold.
I am embarrassed for you. You are dead wrong.
Dennis is among the very best there is out there. People who understand Dennis tend to pay him lots of respect for his knowledge, experience, good-guy attitude, and superb builds.
The user reviews on his Serious Stereo web site didn't occur with smoke and mirrors, there IS a solid design basis there.
Jeff Medwin
No need to be embarrassed for me, Jeff.
applying some of the theory from erasure codes using a linear function as expressed in the polynomial oversampling example.
While I appreciate the abstract intellectual appeal of the information-theoretical approach to analysis of this problem, I believe the best explanation for the documented superiority of prime numbered parallel resistors comes from the domain of quantum electron scattering.
With due respect,
Henry
~!
The Mind has No Firewall~ U.S. Army War College.
Tube Wrangler?
Nice to see you posting here on DIY Tube again.
Is parallel cathode bias resistors something you have tried in the past?
I would think that would lend itself to better internal transfer of energy in a micro current driver stage.
Not that I am using one now, but perhaps in the future for SE direct couple circuit.
DT 667
Audio signal flows through resistors at almost the speed of light.How can what you are saying be true?
I think you are wrong.
Let me restate that.
You said "Whenever you apply two physical things to the same point of force application, any differences between the two objects will show up in the forces that emanate from this combo."
While this is true, the speed at which the force is traveling and the short distances involved would prevent those differences from being audible.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 03/31/12 03/31/12 03/31/12
"I have read in some archived posts"
Don't believe everything you read on the internet.
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